Brothers are better than nothing: first report of incestuous mating and inbreeding depression in a freshwater decapod crustacean

CAROLINA TROPEA; AGUSTINA MARCIANO; LAURA S. LÓPEZ GRECO

ZOOLOGY

ELSEVIER GMBH

Año: 2022 vol. 151

0944-2006

This study aimed at evaluating the effect of one generation of full-sibling mating ontraits related to the fitness of the gregarious freshwater shrimp Neocaridina davidi ,both under optimal and stressful (i.e. starvation) laboratory conditions. Females weremaintained either with their brothers (Inbreeding treatment) or non-brothers(Outbreeding treatment), and the first and second broods were used to evaluate eggproduction and juvenile quality, respectively. The latter was analyzed in a 60-dayperiod following hatching under optimal rearing conditions, and in a 20-day periodfollowing hatching under food deprivation conditions. All surviving females from bothtreatments mated and spawned, indicating that mating with brothers was as likely asmating with non-brothers. Different evolutionary scenarios are discussed for thisoutcome. With respect to offspring production, inbreeding had no effect on fecundityand fertilization success, but negatively affected the number of hatched juveniles.These results suggest that egg loss was higher in inbred clutches, possibly due tolower embryonic survival. On the other hand, the effect of inbreeding on growth wasabsent for embryos and for juveniles under optimal rearing conditions, while it wassignificant for juveniles starved for 10 consecutive days following hatching. Inbreedingdepression for survival was only detected in juveniles from stages S8-S9 under optimalrearing conditions. Overall, the present results show that N. davidi fitness decreasesafter one generation of full-sibling mating. The use of a potentially weak fooddeprivation protocol and/or the evaluation of only one inbred generation could explainthe absence or subtle inbreeding depression for some of the evaluated traits. Noevident relationship between life-history traits and the existence and magnitude ofinbreeding was found when comparing our results with those previously reported inhigh-fecundity marine crustaceans and low-fecundity terrestrial crustaceans.